The invention relates to a method and to a radio communication system for data transmission, especially a mobile radio system comprising wide band channels in which signals are transmitted in accordance with a TDMA/CDMA or CDMA subscriber separation method.
In radio communication systems, information (for example voice, image information, internet messages or other data) is transmitted between transmitting and receiving radio stations (base station and mobilexe2x80x94station, respectively) via a radio interface with the aid of electromagnetic waves. The electromagnetic waves are radiated by means of carrier frequencies which are in the frequency band provided for the respective system. For future mobile radio systems with CDMA or TDMA/CDMA methods of transmission via the radio interface, for example the UMTS (Universal Mobile Telecommunication System) or other third-gene ration systems, frequencies are provided in the frequency band of approximately 2000 MHz.
In radio communication systems, the housekeeping information is used for supplying mobile stations in a radio cell of a base station with the data needed for the radio cell. Housekeeping information is information on the radio cell, its channel structure and services and options available in the radio cell. Thus, the housekeeping information is used by the mobile station for synchronization and selection of the radio cell.
From the GSM mobile radio system and for future mobile radio systems from DE 198 10 285, it is known to provide one timeslot for the transmission of housekeeping information per downlink frame. The first timeslot of the frame is usually used for this purpose. This provides fixed intervals between the emissions of the housekeeping information which are planned in such a manner that a proper evaluation of the housekeeping information and a handover of the mobile stations for all services between various radio cells is supported even in unfavorable traffic load situations and at the maximum permissible speed of the mobile stations. In W-CDMA transmission methods, too, housekeeping information is transmitted continuously in a timeslot or over a number of timeslots in accordance with a frame structure.
The only available criterion for the mobile station of whether registration in the radio cell is possible is the receivability or receptivity of the housekeeping information which is usually sent at high and constant power. If registration, i.e. the setting up of a connection, is possible, the available services can be requested. These are voice or short message services in the GSM mobile radio system.
If, however, it is intended to extend the range of services on offer, it must be ensured even for the most sophisticated service that this service can also be received well with adequate receivability or receptivity of the housekeeping information. This means severe restrictions for the radio network planning.
It is accordingly an object of the invention to provide a method and a radio communication system with a number of services which overcome the above-mentioned disadvantageous of the prior art apparatus and methods of this general type, and which allow greater flexibility in the radio network planning.
With the foregoing and other objects in view there is provided, in accordance with the invention a method for transmitting data between a base station and a plurality of mobile stations in a radio communication system. The method includes offering a plurality of services for a plurality of mobile stations via a radio interface in a radio cell of a base station. For at least one service, an individual parameter with respect to a required receivability or receptivity is determined. The parameter is transmitted from the base station, and the parameter is received and evaluated with one of the plurality of mobile stations. In the one of the plurality of mobile stations, a current receivability or receptivity of emissions from the base station is compared with the parameter. The one of the plurality of mobile stations requests or does not request the service, dependent upon the result of the comparison.
An individual parameter with respect to a necessary receivability or receptivity is determined, and sent by the base station, for at least one service in a radio communication system which offers a number of services for mobile stations in a radio cell via a radio interface. The parameter is received and evaluated by a mobile station and then the current receivability or receptivity of emissions of the base station is compared with the parameter and the service is requested by the mobile station in dependence on the result of the comparison.
Thus, the service request is no longer dependent only the current receivability or receptivity of emissions of the base station. The current receivability or receptivity must be additionally compared with the service-specific parameters with respect to the receivability or receptivity for a service. If this parameter is satisfied, this service can be requested. The planning of control channels as a basis for determining the receivability or receptivity is thus largely independent of the planning of the coverage with the individual services.
Each service can have its own range which does not mandatorily have to correspond to the size of the cell. At the same time, the mobile station can locally request an authorization for a service before there is access to the radio interface.
In accordance with an added feature of the invention, the parameter is a value used to refer to a maximum permissible attenuation, a minimally required received field strength, a minimally required signal/noise ratio and/or a maximum permissible signal delay. It is also possible to send and evaluate a number of parameters per service. Where there are several evaluated parameters, the reliability is increased that the service can also be reliably maintained after the connection has been set up.
In the determination of the parameter by the network, a maximum data rate per service or for the entire radio interface, a quality of service to be guaranteed for the service and/or any current utilization of the radio interface is taken into consideration. It is thus possible to form for each service or at least for the services, the ranges of which do not continuously coincide with that of the housekeeping information, one or more criteria which enable each mobile station to determine the availability of a service without prior interaction at its current position and under its current conditions of reception.
In this context, the individual services are voice services, emergency call services, short message services, teletext services, facsimile services, an internet service or image transmission services. The radio communication system can offer these services without their availability having first to be tested by the mobile station. Any unnecessary loading of the radio interface by an unsuccessful request of a service is avoided if the request is advantageously blocked with respect to this base station in the case of a negative result of the comparison. This means that, as long as the current conditions of reception are not improved, no request is sent to the base station by the mobile station.
In accordance with an additional feature of the invention, the current receivability or receptivity is derived from the evaluation of received signals of a control channel and the radio interface is organized with wide band channels in accordance with a TDD transmission method. This guarantees the application of the method according to the invention in third-generation mobile radio systems which, with very different cell sizes, asymmetric utilizations of the radio interface, many different services and applications, make great demands both in the full-coverage mobile radio system and in the domestic area.
With the foregoing and other objects in view there is provided, in accordance with the invention a radio communications system in which a plurality of services are offered for a plurality of mobile stations via a radio interface in a radio cell of a base station. The radio communications system includes a base station and at least one mobile station. The base station includes: a signal conditioning facility for forming signals with information to be transmitted; a controller for determining an individual parameter with respect to a required receivability or receptivity for at least one service; and a transmitting facility for transmitting the signals, some of the signals containing the parameter. The mobile station includes: a receiving facility for receiving and evaluating the parameter; an evaluating facility for comparing a current receivability or receptivity of emissions from said base station with the parameter; and a calling facility for requesting a service dependent upon a result of the comparison.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method and radio communication system for data transmission, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.